1. Field of the Invention
This invention relates to manufacture of head gimbal assemblies, known as HGAs. More particularly, the invention relates to manufactures and manufacturing steps that simplify and make more accurate and less time-consuming the juxtaposing of the slider with the dimple when mounting the slider to the flexure tongue. The invention substitutes added optically readable indicia for the outlines of the dimple as the locating criteria for the slider, thus ensuring accurate placement of the slider every time.
2. Related Art
In the manufacture of suspensions comprising a load beam, a flexure attached to the load beam and having a tongue, and a slider, mounted for gimbaling movement around a dimple defined by the flexure tongue or the load beam rigid portion, the positioning of the slider by automatic equipment is essential to efficient manufacture. A misplaced slider, that is a slider that is not properly aligned with reference to the dimple, will not gimbal properly or predictably and is a costly defect that reduces manufacturing yield. Taking additional time to properly place the slider increases costs in a very cost conscience industry.
This application refers to sliders as the mounted element. The term slider herein is used to encompass not only the slider itself, a typically ceramic body designed to fly over the rotating disk in a disk drive, but also to include the read-write head carried within the slider body and connected to the device electronics.
The need for increased accuracy in positioning of sliders must be met at no greater expenditure of manufacturing time. This can be achieved by the use of automatic positioning apparatus using optical reading to locate the correct position. Presently available optical readers, known per se, cannot, however, read with certainty the location of the dimple because the dimple, being an upset or etch formed boss, lacks clear delineation at its junction with the surrounding wall of the flexure tongue or load beam rigid portion. That is, there is not a sufficiently sharp, or uniformly distributed, target for the optical reader to use as a marker for positioning the slider relative to the dimple.
It is an object, therefore, of the present invention to provide markers of such sharpness and uniformity of distribution that positioning equipment can read and position the slider with reference to them, as opposed to the dimple, with increased accuracy, better speed and fewer defects. It is a further object to provide a system of optically readable indicia, typically geometric shapes, arranged in a pattern useful in the invention method. It is a further object to provide a series of such indicia arranged in such proximity and uniformity of pattern relative to the dimple as to be useful as a proxy for the dimple in locating the slider properly on the flexure tongue. It is a further object to provide an etched dimple in the form of a dimple post that is so small as to be normally hidden below the flexure tongue. It is a further object to provide optical readable indicia laterally adjacent the dimple post to enable optical reading of the indicia although the dimple post is hidden from view, and thus to enable the mounting of the slider with great accuracy.
These and other objects of the invention, to become apparent hereinafter, are realized in a head gimbal assembly of a load beam comprising a wall, a flexure attached to said load beam and having a tongue, and a slider attached to a first side of the flexure tongue, the load beam defining a dimple comprising a solid post extending normal to the load beam wall and positioned, sized and shaped to allow gimballing movement of the slider by contact with a second side of the flexure tongue, the dimple post being hidden from view from the flexure tongue first side, and optically readable indicia formed in the load beam wall laterally of the dimple sufficiently to be visible from the first side of the flexure tongue for precisely locating the slider opposite the dimple post be reference to the optically readable indicia rather than the dimple post.
In typical embodiments, the load beam is locally etched to define the dimple and flexure tongue is locally narrowed opposite the indicia to facilitate location of the indicia immediately adjacent the dimple post while maintaining the indicia visible from the flexure tongue first side, the dimple post is cylindrical, and the optical readable indicia comprise left and right hand holes on a common axis with the dimple post, the flexure tongue having a dog-bone shape to expose the optically readable indicia.
In its method aspects the invention contemplates the method of mounting sliders onto load beams of flexure tongues in position opposite the dimple in a head gimbal assembly comprising a load beam, a flexure having a tongue and a slider, and wherein the load beam defines a dimple as an upstanding post smaller in width than the flexure tongue, that includes marking the situs of the dimple with optically readable indicia comprising left and right load beams holes laterally spaced from the dimple post sufficiently to be visible when the dimple post is not visible, and guiding placement of the slider on the flexure tongue with reference to the optically readable indicia rather than the dimple.
In this and like embodiments, also, there is included forming the dimple post by etching the load beam, and shaping the flexure tongue to expose the optically readable indicia for reading.